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I have 2 (S7-315-2 DP) PLC. How I can send and receive data thru Profibus DP. I don’t have any CP only PLC with DI, DO blocks. I try to make connection but it is like not possible because I don’t have CP block. DP_Send block shows error (address not found). Witch command I must use?

HelloIt's not possible to make a S7 connection between 2 S7-315-2DP(Master) without CP's. However You can connect them through a DP/DP Coupler. Only the max of data is 244 bytes for inputs and 244 bytes for outputs, In this way it is possible to communicate over profibus DP without CP's. If the amount of data isn't enough, then insert another DP/DP Coupler.

There areseveral possibilities to communicate. I suggest using the DP interface.

1. If I am not mistaken you are not using the on board DP interface for communication with DP slaves. In this case you could configure one of theCPU's as an intelligent DP slave.

2. If they both have to be master, then I suggest using a DP DP coupler.

3. You could also try to use MPI via global data or X_PUT X_GET, but personally I am not in favour of these solutions. One of the reasons is that with DP you will have some sort of determinancy, i.e. you can calculate/estimate the response time of your system.

4. How much data do you want to send? If you have to send a lot of data not time-critical you might consider using a CP 342-5 or even an Ethernet solution.

If you use option 1 or2 and you want to send the data in one consistent block, use SFC 14 and 15.